The invention relates generally to the removal of undesired components from fluids.
Impurities in air, which are detectable as odors, today pose a continuously increasing environmental problem. The sources of these nuisances range from animal breeding establishments to reconditioning plants for the clarification of sediment to foundries in which, for instance, formaldehyde must be driven off. The impurities are often in the form of vapors and, even when present in the most minute concentrations, are already effective for causing a considerable nuisance.
As a rule, the present state of the art offers three distinct and separate methods for the removal of such impurities. These are as follows: (1) The so-called combustion method; (2) The activated carbon filtering method; and (3) The wash method.
Each of these three methods, however, possesses certain disadvantages. Insofar as the combustion method is concerned, there exists the problem that, even when only the most minute traces of impurities are present in a gas, it is necessary to subject the entire quantity of gas to combustion. This results in enormously high energy expenditures.
In contrast, the method using activated carbon is economically feasible only when the concentration of impurities is very low. The reason resides in the fact that the cost of activated carbon is very high.
The so-called wash method using water or leaching solutions such as, for instance, soda lye in those cases where phenols and formaldehyde are driven off, exhibits the following disadvantages: Where the wash is effected using water alone, it is necessary for the discharged water to contain such a small quantity of impurities that the collected impurities are not again liberated.
On the other hand, where the wash is effected using a leaching solution, it is necessary to chemically prepare the lye or acid washing solution. Normally, this preparation cannot be undertaken at the location where the impurities are driven off and, consequently, it is necessary to prepare the washing solution at a chemical plant and to then transport it to such location. This involves very high transportation costs. In addition, there is the consideration that, at present, there is no chemical plant on the European market which advertises itself as ready to prepare lyes such as, for instance, soda lye, the latter which is used for washing out phenols and formaldehyde.